There is a substantial body of prior art patents concerned with tin or tin alloy electroplating baths and processes for utilizing the same. Some of the more relevant patents for the present purposes include U.S. Pat. Nos. 3,730,853 (Sedlacek et al.); 3,749,649 (Valayil); 3,769,182 (Beckwith et al.); 3,785,939 (Hsu); 3,850,765 (Karustis, Jr. et al.); 3,875,029 (Rosenberg et al.); 3,905,878 (Dohi et al.); 3,926,749 (Passal); 3,954,573 (Dahlgren et al.); 3,956,123 (Rosenberg et al.); 3,977,949 (Rosenberg); 4,000,047 (Ostrow et al.); 4,135,991 (Canaris et al.); 4,118,289 (Hsu); and British Pat. Nos. 1,351,875 and 1,408,148.
Despite the existence of this extensive literature and the various formulations which have been suggested for commercial applications, there is still a need for electroplating baths which will effectively deposit bright metallic tin on various substrates. Another important characteristic is bath stability, especially premature tin compound precipitation in the bath. The variety of bath formulations proposed heretofore reveal, moreover, that all of the ingredients employed in the bath formulation must be taken into consideration not only with respect to the type of deposit obtained but also with respect to questions of bath stability, by-product formation, etc.